Whatever it was doing to her sister, it wasn't good. Claire grabbed the nearest lamp, ran over to the beast and smashed the porcelain over its third head. The head shuddered and growled. All three heads turned to Claire.
"You..." said the first in a bestial but vaguely female voice.
"just couldn't have waited for your turn..." said the second.
"could you?" finished the third.
The beast twitched and shifted. Its forepaws expanded into clawed digits while its hindpaws widened into taloned feet. The demoness stood up, lifting Vicki up with its phallic tentacle still imbedded in her. Her heads shifted on their necks to accomodate a bipedal viewpoint.
Vicki squealed as the beast continued to fuck her. Claire looked around for a weapon, but could only find light objects to hurl at it.
The demoness drew Vicki against her in an embrace. Claire watched in horror as her sister seemed to be absorbed into the flesh of the monster, her extremities splayed outward. Vicki's toes erupted in long ebony claws as the flesh of her feet turned red to match that of the demon's. Her arms turned crimson as well. Both her legs and arms lengthened to that of the monster's. Her breasts slid under the monster's own nipples, forming an additional dark set.
Vicki's limbs lengthened to that of the demon's own, transforming the beast into a four-armed, four-legged monstrosity. Finally, Vicki's head slid alongside the other three where it began to warp and twist, her features becoming more demonic and lupine.
"Sister!" It growled. "Won't you join us?"